how do i wire up a led power button so it lights up?

**megagoo** · 02-21-2007, 09:41 PM

http://www.frozencpu.com/products/19...ion.html?tl=g4

how do i wire this up to my computer?

firstly, i do understand that i need to hook up to the + and - led connectors.. i was able to get the button itself working but not the light. i had purchased the cable here: http://www.frozencpu.com/ele-175.html which i am under the assumption that all i do is hook this up to the power led pins on my motherboard. i did that and it didnt work. my positive and negatives were correct.

i have a m2-atx with a power-led but i am not sure what the difference is between that one and the one on my mobo. . i didnt try that yet because i would have to find a 2-pin cable to hook into the m2-atx

the page says i can wire it up to my carpc's 5v if i tack on a resistor but i'd rather be able to power it off of the motherboard.

any help is appreciated
thanks
eddie

**MrJamieR** · 02-21-2007, 09:54 PM

The page you've linked to says you can power the "LED from either your motherboard's 5V DC output or your Power Supply's 12V DC output" and gives you the resistor values for each option. So your preference for powering from your mobo is acheivable. Have you tested the LED is working? (Try using a small 3.3V battery.) It's either broken or it ain't getting power.

DIGItonium · 02-21-2007, 09:59 PM

Since you are using the M2-ATX, simply wire it up to the LED +- terminals on the M2-ATX. It already has a current limiting resistor.

**megagoo** · 02-21-2007, 10:20 PM

Originally Posted by DIGItonium

Since you are using the M2-ATX, simply wire it up to the LED +- terminals on the M2-ATX. It already has a current limiting resistor.

great i will try that then. i consulted the manual but it didnt explain it whatsoever. just said j5: LED

**megagoo** · 02-27-2007, 12:20 AM

Originally Posted by megagoo

great i will try that then. i consulted the manual but it didnt explain it whatsoever. just said j5: LED

having problems. LED on mt2 atx not working on the bulgin switch.. it reads a 6v output which i need 3.3 .. ive tried about 30 different resistors on it adn no dice.... but with a certain resistor it works on a 9v battery. losing my mind here

**h3rk** · 02-27-2007, 01:33 AM

According to Kirchoff and Ohm; if you have a 6V source and a load that needs 3.3V, 0 = -6 + 3.3 + Vr \ Vr = 2.7 & Vr = Ir * Rr \ Ir could be interpretted from the manufacturer's requirements @12V ->420ohms and @5V ->70ohms
Using V=IR, I get a range of about 30 to 70 milliamps.
Vr/Ir = Rr
2.7/.030 = 90 ohms
2.7/.070 = 38 ohms

A resistor within that range should drop current to an acceptable level and have you seeing blue. If you used a smaller resistor in your testing you may have let out some of the LED's magic smoke.

**megagoo** · 02-27-2007, 05:55 AM

so you're saying i need a resistor 38 - 90 ohms? i tried a ton of resistors on it already using alligator clips. i will try that after verifying that its still lighting up off the 9v battery that i got it to work with earlier with a 150ohm

the weird thing is is that on all the resistors i put a volt meter on, the voltage came out to 1v and less on my 6v led output.

Originally Posted by DIGItonium

Since you are using the M2-ATX, simply wire it up to the LED +- terminals on the M2-ATX. It already has a current limiting resistor.

this cant be correct because the led pins read 6v and the switch requires 3.5

is it possible for it to work on 9v but not on 6v (or 12v or 5v... i have all 3 options in the car). or could i even use the 3.3v output on my power supply with no resistor? this is incredibly frustrating just to have a little light on a button

**h3rk** · 02-27-2007, 07:49 AM

9V / 150ohm = 60 mAmps. So that jives with what I had figured.

With that in mind, you may want to use a resistor closer to 38 ohms.

I don't however have the greatest confidence in the resistors needed on the link you provided;

"We were informed that the correct resistors for the switch's LED are the following:

12 V DC source: 420 ohms
5 V DC source: 70 ohms"

It just doesn't paint a picture of confidence.

It shouldn't be so frustrating.

The 3.3V in your power supply should have a limiting resistor, and be acceptable to use. You could use a test resistor (more accurate than +-5%) measure the current, and see.

**ShawJohn** · 02-27-2007, 08:10 AM

power the LED straight from the Power LED feed on the M2, that way the switch will only illuminate when power is available to the PC. Or you could use that as a HD activity LED if you wanted to keep it clean and simple with only the one switch visible.

**megagoo** · 02-27-2007, 09:29 AM

Originally Posted by h3rk

The 3.3V in your power supply should have a limiting resistor, and be acceptable to use. You could use a test resistor (more accurate than +-5%) measure the current, and see.

how do i test this? beforei realized it was the wrong way to do it, i was putting a volt meter at the end of the resistor with no load. as in

+ terminal>resistor>meter tip
-termal> meter tip

this was reading the same voltage as the source. so i gess you have to have a load on it. that load is my switch which i'd rather it not be so that i dont burn it out if my current is too much. so how do i check voltage w/o using my expensive switch as a load? is it possible?

thanks for the help btw